The specific aims of this research are: a) to study the early development of temperamental self-regulation as demonstrated in children's caution and verbally regulated ability to delay, and b) to assess components of visual-spatial attention, chart their development, and relate them to concurrent measures of children's temperamental emotional reactivity and self- regulation. Research on individual differences in self-regulatory capacities is of basic importance to the socialization process. Much of the content of socialization involves the inhibition of acts that may be inherently rewarding but are proscribed by the culture. A longitudinal study allows investigation of the relationships between behavioral inhibition to fear-inducing stimuli, the capacity to inhibit a previously rewarded response, and components of attention. Three sets of data will be collected in a laboratory study of children seen longitudinally at 6, 9, 12 18 & 48 months of age. These include temperament data on smiling and laughter, fear, and behavioral inhibition as assessed by laboratory observation and by parent report, assessments of older children's verbally regulated self-control, and measures of visual attention developed originally by Posner for use with adults. Attention measures include an assessment of temporal versus nasal biases in attention, measures of facilitation and inhibition related to parietal function and measures of inhibition of return related to collicular control. This research allows us to study the development of self-regulation at both behavioral and neuropsychological levels and to trace the early development of important individual differences in impulsivity and self control.